Furnace construction



1, 1944- J. s. WALLIS ETAL 2,340,239

FURNACE consmucmon Filed Sept. 11, 1942 I IN VEN TORS. Jab/7 5. 14 4/03 Jab/7 14 7/7/"0 mar/00 tion chamber Patented Feb. '1', 1944 UNITE STATES PATENT OFFICE- memos cons'mucnon 10:3! sglglins, Izrlen, and mm w.

m, m Development Company,

pontion of Delaware Application September 11, 1942, Serial No. 458,048 3 Claims. (0]. 122-356) combustion chamber by burners arranged to diswillflrsttraversetheinnerbank andthentheouterbankoitubessothat coolerflmdwillflowthroushtbeinnerbank tubes and the more fluid through of I 7 andwithinthecomnassoi ottuhee for reflecting radiant heattowardtheportionsoithetubesextendina thronghthelowerorradiantsectionoitlmcombustionchamberandiordeflectingthecoinbnssurfaces for increasing heat suspendedinjtlie nl erpcrtionoi the amount of heat is combusti Throchmorannular space. Radial fins may; be used on the pper portions of the tubes absorption.

All of the combustion gases from the combustion chamber pass through the annular space and about the heat exchange I in. Since the coolest fluid is flowing through these tubes, the maxim covered from the flue gas. Thus, a low flue gas By the double bank.

bank and thence ers between the innerand outer banksin the desired direction, as well as the controlvof firing may be fired to up to temperature and theouter burners fired at a'variable rate accordingfto their position and the direction of flame projection to obtain a rapidlyincreasingtemperaturegradientintheouter bank, ora low increasing 'tempera or a relatively constant temperature balance the heat absorption of reactions portion or the furnace. An important object of our invention is the o! a furnace on cases. Another object or our invention is to provide a with to provide exchange tubes positioned there-' tube arrangement, includ-. v ing theicirculation of'fluid first through the inner through the outer bank, to-

brlngthe. fluid rapid y construction wherein a ibsorbed'i'rom the:

In the accompanying drawing, wherein for the purpose of illustration is shown a-preferred embodiment of our invention, the furnace is mounted upon a support ll and comprises an outer cylindrical casing ll of sheet metal lined with a refractory material 12. The space within the casing comprises a combustion chamber.

\ Enclosed within the combustion chamber is a circular inner bankof vertical heat exchange tubes designated generally by the numeral l3 and a circular outer bank of vertical heat exchange tubes designated generally by the 'numeral ll. As shown in Fig. 2, the outer bank of tubes I4 is disposed in proximity to the inner wall of the combustion chamber and the inner bank of tubes I3 is concentrically located within the outer bank of tubes. The heat exchange tubes preferably comprise U-shaped units having their open ends extending through the refractory material comprising the top of the combustion chamber and supported by U- shaped brackets i5. Adjacent ends of the respective units-are connected by return bend headers i6. This construction permits the tubes to be. easily cleaned in situ and removed for replacement or,.repalr since it is only necessary -to remove the headers I in order that the U- shaped units may be pulled vertically from the combustion chamber.

Extending through the refractory material forming the bottom of the furnace are a plurality of directional burners ll. Combustion fuel is supplied to the burners through pipes it. The burners are rotatable and may be adjusted to'project the heating gases onto the surfaces of the tubes into various parts of the combustion chamber in order to obtain the desired heat .distribution. Additional-burners llo positioned in the annular space between the inner and outer tube banks are supplied at the top of the combustion chamber for a, more accurate heat control. The combustion gases rise upwardly and are discharged from the furnace through a stack or flue ll.

As shown in Fig. 1,"the refractory material forming the top of the combustion chamber has a centrally located, upstanding neck 12a which comprises the lower portion of the stack I. The tubes of the inner bank I! are substantially 7 longer than the tubes of the outer bank It and the upperportions thereof extend into the throat of neck l2a.

- A fluid inlet "a connects with the inner bank of heat exchange tubes I3 and a fluid outlet Ila connects with the outer bank of heat exchange cooperates with neck |2a to provide an annular space '22 into which the upper portions of the inner heat exchange tubes I! extend. The cone 2! besides reflecting heat from the burning gases against the inner bank of heat exchange tubes also deflectsthe gases into the annular space 22 so that they flow around the upper portions of the inner heat exchange tubes It. The portions of tubes l3 extending into the annular space 22 may have radial fins 22 which offer increased heat absorption surface.

All of the combustion gases must pass through annular space 22 before entering the flue l9; Since the fluid to be heated flrst traversesthe inner bank of tubes 13, the fluid in these tubes is relatively cool and capable of absorbing considerably greater quantities of heat than the fluid traversing the outer bank of tubes It.

It may thus be seen that we have accomplished the objects of our invention. By providing inner and outer banks of vertical tubes concentrically arranged. flring said banks within the inner bank and at the top and bottom of the annular space between the banks, controlling direction and ratio of flring the burners and by controlling the fluid flow through the respective banks we are able to obtain wide variations in the temperature gradient of fluid being heated together with a high degree of efliciency.

It is to be understood that the form of our invention herewith shown and described is to be the scope of the appended taken as a preferred example of the, same and that various changes in the size, shape and arrangement of parts maybe resorted-to without departing from the spirit of our invention or Having thus described our invention, we claim:

1. In a furnace construction, a. wall of refractory material providing a combustion chamber, a fine passage opening through the top of the combustion chamber, inner and outer banks of interconnected heat exchange tubes within the combustion chamber, the upper portion of the inner bank of tubes extending into the flue passage, and

a deflector within the inner bank of heat ex-.

tubes ll, the two banks of tubes i3 and it being connected by across connection la. The arrangement is such that fluiddelivered to the furnace through inlet its will traverse the inner bank of tubes it before being conducted by pipe is to the outer bank of tubes II. The fluid then traverses the outer bank of tubes and is discharged from the furnace through outlet a, As the combustion gases rise within the furnace,

they give up heat to the fluid in the heat exchange tubes.

Since the fluid is usually delivered to the furnace in a 'relatively cool condition," the fluid traversing the inner bank of" tubes, II will be relatively cooler than the fluid traversing the outer bank of tubes ll. By the time the fluid has passed through the outer bank of tubes, it is in a relatively heated condition.

In order to obtain a more even distribution of radiant heat upon the inner bank of tubes it,

change tubes for directing the discharging combustion'gases about the inner bank of tubes and intimately into contact with the portions thereof projecting into the flue passage.

2. In a furnace construction, a wall of refractory material providing a combustion chamber, a flue passage opening through the top of the combustion chamber, inner and outer banks of in terconnected heat exchange tubes within the combustion chamber, the upper portion of the inner. of tubes extending into the flue passage, a deflector within the inner bank of heat exchange tubes for directing the combustion gases intiinately about the portions of the tubes projecting bank into the flue passage, and extended surfaces on the portions of the inner bank of tubes projecting into the flue passage for increasing heat absorption.

- :8. In a furnace construction, the combination with a combustion chamber surrounded by en- 'closing walls' of refractory material having a 1 source of combustion gases and an outlet flue, a a

5 surfaces.

thereof located in the radiant zone and portions in the convection zone, said tube portions in the radiant zone being plain surfaces and said portions in the convection zone having extended JOHN s. WALLIS. JOHN w. 'I'HROCKMORTON. 

